The present invention relates generally to methods and systems for printing computer generated images and more particularly to methods and apparatus for formatting a sheet in preparation for printing on a printing device.
A computer system can output data to a wide variety of output display devices. Output display devices such as laser printers, plotters, imagesetters, and other printing devices produce an image or xe2x80x9cvisual representationxe2x80x9d on a sheet of paper or the like. A printing device can print dots on a piece of paper corresponding to the information of a bitmap (or pixelmap where a pixelmap is characterized as having a depth of two or more bits). A xe2x80x9crasterxe2x80x9d printing device creates a visual representation by printing an array of pixels arranged in rows and columns from the bitmap.
One type of printing device is a printing press. A printing press may be used to produce books, newspapers, pamphlets, posters and other single and multi-page printed matter. The printing press advantageously prints multiple pages of printed matter at the same time onto a single sheet. Other devices used for printing multiple pages at the same time include imagesetters and plate setters.
When printing multiple pages, the individual pages are arranged in one or more sheets. Each sheet includes a layout of pages that may be ordered or otherwise optimized to facilitate post-printing processes. Imposition is the pre-printing process of arranging the pages for a sheet to achieve a proper sequence or position of each page relative to other pages. Imposition is performed to facilitate post-printing processes. These processes include fold and cut operations followed by some form of binding.
Conventional imposition processes are executed on a computer workstation prior to the printing process. An imposition process operates on one or more page description language (PDL) files or image data files and layout information for a given sheet. The PDL files are representative of the various pages (or sub-pages) of content to be displayed on a given sheet. The layout information describes how the pages are to be arranged to achieve the desired output result. The output of a conventional imposition process is a single PDL file that includes all the data required (including external references if any) to print the sheet by a printing device.
A process flow for printing a sheet onto an output media is shown in FIG. 1. A plurality of pages of content 2 are arranged to form a sheet 4 by executing an imposition process 3. The imposition process receives as inputs the individual page files, which may be in the form of PostScript(copyright) files, printers marks or other objects to be marked on the page, and layout information 5. Layout information 5 describes the layout of the sheet including the location of each object on the sheet. The output of the imposition process is a PDL file that describes the entire sheet 4. The PDL file describing the sheet is transferred to a printing device 6 for printing.
Printing devices that produce output in response to PDL input are widely used. In order to produce a finished sheet, the printing device interprets the data contained in the PDL file, renders objects within the data into bitmaps, and after all objects for the sheet are rendered, prints the sheet. More specifically, printing device 6 includes a raster image processor (RIP) 8. RIP 8 renders objects within the PDL file into bitmaps which are transferred to a print engine (not shown) for printing onto the output media.
In general, in one aspect, the invention provides a method for imposing and rendering image data. The method formatting the image data for a surface of a media sheet in an output device space and including receiving one or more page description files defining one or more objects to be located on the surface of the media sheet, receiving a job ticket defining a layout of the objects on the surface in a sheet-defined space. Prior to ripping, the layout of the objects is transformed into output device space including rotation or translation of the objects. The objects are ripped creating raster data that is oriented in output device space. The raster data is blitted in blocks without shifting the raster data.
Aspects of the invention include numerous features. The method can include printing the raster data on the surface of the media sheet. An ordered list of objects can be constructed for the surface from the position of each page in output device space and the objects can be ripped in order in accordance with the ordered list. The step of blitting includes compositing objects into a sheet frame buffer. The objects can be ripped in parallel.
The job ticket definition includes a translation matrix for each object where the translation matrix describes a location of the object on the surface in sheet-space after translation or rotation of the object to facilitate post printing operations. The translation matrix may include transformations from bottling and shingling operations. The method includes adjusting rip parameters for the surface in accordance with the output device and ripping the objects using the adjusted rip parameters. The page description files are PDF files. The method includes translating all page description files received into PDF files prior to ripping. The method can be performed in a printing device where the printing device is selected from the group of an imagesetter, a digital press, a printing press and a plate setter.
The step of ripping includes rendering each object creating raster data oriented in output device space. The step of blitting includes compositing objects into a sheet frame buffer. The step of blitting includes compositing the objects into bands for storage in a band buffer. The step of transforming the layout includes transforming the layout to support bottling or shingling operations.
In another aspect, the invention provides a method for bottling image data and includes receiving one or more page description language files defining one or more objects to be displayed on the surface of the media sheet, bottling the objects including defining a rotational or translational transformation of the objects, ripping the objects to produce raster data that is bottled and blitting the raster data.
In another aspect, the invention provides a method for shingling image data and includes receiving one or more page description language files defining one or more objects to be displayed on the surface of the media sheet, shingling the objects including defining a rotational or translational transformation of the objects, ripping the objects to produce raster data that is shingled and blitting the raster data.
In another aspect the invention provides a printing device configured to receive a plurality of page description language descriptions of pages to be printed on a sheet and includes an assembler connected to receive a job ticket including layout and page identifier information for one or more objects to be printed on a sheet and operating to transform the objects from a sheet-defined space to a printer device space. The printing device includes plurality of render engines each operating on objects to produce raster data associated with portions of the sheet and blitter engine operable to blit the raster data in blocks without shifting the raster data.
Among the advantages of the invention are one or more of the following. Pages of a sheet may be ripped in parallel. Bottling and output media orientation issues can be resolved prior to rendering to facilitate efficient post RIP blitting operations.
Other features and advantages of the invention will become apparent from the following description and from the claims.